[DMK]

I have one of my 1911s at the 'smith right now because I had experienced some rather unpleasant two and three round bursts with it.

Before taking it out to fire it, he looked it over quickly and mentioned to me that he didn't see anything obviously wrong with it. Although he will test it at the range, he did mention that my problem may be in my technique, that basically I may be bump firing it.

So assuming that's correct, how do I ensure that I won't be doing that again? I'm thinking that I should be very concious about a tight grip and trigger follow through. Any other tips or comments?

Has anybody had this happen to them where it was not caused by a problem with the gun?

[Sean Smith]

Um, if you are shooting triples with it I am 99% sure that the gun is busted and the 'smith doesn't want to admit it or is too stupid to figure it out. I don't suppose this 'smith did a trigger job on it by any chance?

The fact that your other 1911s don't shoot 3-round bursts is a strong hint that your technique is not at fault. Furthermore, I can't imagine how someone can unintentionally get 3-round bursts from faulty technique alone.

[Tamara]

What Sean said: "Doubles" are bump-firing; "triples" are a boogered trigger job. :uhoh:




Speaking of which, did y'all know that recent production Third Generation S&W autos have plastic disconnectors? Now there's something that'll give ya the warm'n'fuzzies! :scrutiny:

[Graystar]

If it's only happening on one of your guns, then I'd guess there's a problem with the gun.

I don't think you can bump-fire a hand-gun. It's more of a rifle thing.

Essentially, bump-firing is holding the gun firmly with one hand while the trigger finger is held stationary and trigger hand is more or less held independent of the gun (not really gripping.) You push the gun forward against the trigger finger to fire. The recoil pushes the gun back, resetting the trigger. If you held the gun firmly, the foward motion of the gun will bring it in contact with your trigger finger and fire the weapon again.

Firing a handgun is a one-handed operation. You can use the second hand to steady, but not to hold.

Have you ever found the hammer in the half-cocked position?

[Sean Smith]

Let's consider how the 1911 works... it is designed so that if you hold the trigger back after firing, it WON'T go off when the slide goes back into battery. And naturally, it isn't supposed to go off if the trigger ISN'T pulled. You can demonstrate this with an unloaded gun very easily; with the slide locked back, hold back the trigger then lower the slide... the hammer stays cocked on a properly functioning 1911. If it is broke, the hammer will follow the slide down. When you release the trigger, you will hear the disconnector "click,"at which point you can re-pull the trigger and the gun will go off. In fact, this technique is recommended by some for lowering the slide on a gun with a very light trigger job.

So, to accidentally set it off twice in a row, you'd have to pull the trigger, release it, and accidentally pull the trigger again right after the gun has gone back into battery (because of the disconnector). I guess I can imagine how you could do this with an improper grip on a gun with a very light trigger, but you'd have to work at it.

[DMK]

Thanks for the comments folks.

BTW: I have tried to get the hammer to drop unintentionally with snap caps and couldn't do it. As far as I could tell statically, the disconnector worked and neither the full cock notch nor half cock notch would let the hammer drop. So whatever is happening, it is only happening when live firing.

Greystar: I don't think it is an impossible scenario. When firing, the gun moves backward from recoil. If it moves backward faster than your finger, a second shot could be fired if the trigger resets before your finger moves back more or if the gun bounces foreward again into your finger. Tamara and Sean raise a good point though. It may be highly unlikely that would cause a triple.

[Graystar]

When firing, the gun moves backward from recoil. If it moves backward faster than your finger, a second shot could be fired if the trigger resets before your finger moves back more or if the gun bounces foreward again into your finger. Yes, and therein lies the reason why it's impossible. The finger is connected to your hand, and your hand is wrapped around the grip, making it impossible for the recoil force to move your hand, but not your finger. Remember, at the time the gun goes off your finger is exerting around 5-6 pounds rearward. There's no way the gun will pull away from that.

I think you'd have to have a strange two handed grip where you are gripping the gun with one hand but using a finger on the other hand to press the trigger. Then the gun can pull away from the trigger finger.

Yeah, live fire can make guns do thing they wouldn't otherwise do. Here's a thought...broken firing pin spring? Take a shot, then check the round in the chamber. See if the primer has a dent in it.

[larryw]

Combining the fact that guns rotate and twist when fired with the fact that human hands do not yield a 100% solid grip (skin, muscles, etc. allow some movement) bump fires are entirely possible. Especially when shooting a gun that had a trigger job that yields a very short reset. Been there, done that.

If a double is possible here, why not a triple? Or a quad?

Really concentrate on keeping locked trigger back as the shot breaks.

[7.62FullMetalJacket]

Don't fix it, i'll buy it:evil:

[DMK]

Don't fix it, i'll buy it Nice try. ;)

[JohnKSa]

Highly unlikely that you could get a triple with an accidental bump-fire.

Doubles are another story.

[Standing Wolf]

Speaking of which, did y'all know that recent production Third Generation S&W autos have plastic disconnectors? Now there's something that'll give ya the warm'n'fuzzies!

Genuine traditional plastic, or just the new cheap stuff?

[SnWnMe]

Speaking of which, did y'all know that recent production Third Generation S&W autos have plastic disconnectors? Now there's something that'll give ya the warm'n'fuzzies!

Shoot, half of a Glock is plastic and nobody's complaining.

[larryw]

Highly unlikely that you could get a triple with an accidental bump-fire.

Why's that John? Is there a difference between the first/second shot and the second/third shot?

[JohnKSa]

You have to be ready to control the recoil and maintain the grip configuration that allowed the bump-fire if you want to get a string of quick shots, even with a rifle which is a good bit easier to bump-fire than a pistol, IMO.

The muzzle of a pistol will rise very quickly after a shot or two and will change the way the grip, trigger finger and gun interact.

The only way I've seen someone bump-fire a pistol on purpose was to hold the gun with one hand and use the finger from the other hand to operate the trigger.

I can see how a similar thing might happen with only one hand and cause a double, but the recoil and muzzle rise are going to make a triple very unlikely.

[Rich in VA]

I think I'd look at a couple of things here.

Could your sear spring be a bit slack?

Maybe the overtravel screw is turned in too far?

Either one could keep the sear from resetting properly.

Keep us posted, these things are always good to learn on.....

Rich

[BluesBear]

My first inclination is to suspect a weak or deformed sear spring that is allowing the sear to release the hammer a second or third time due to sympathetic vibrations that are only present during/after liv fire recoil.

[c_yeager]

Speaking of which, did y'all know that recent production Third Generation S&W autos have plastic disconnectors? Now there's something that'll give ya the warm'n'fuzzies!


Shoot, half of a Glock is plastic and nobody's complaining.

And yet even Glock has chosen NOT to use plastic disconnectors.

And while it IS possible to bump fire a 1911 its pretty hard to accidentaly do it three times without trying. Sounds like a messed up gun to me.

[DMK]

Here's a thought...broken firing pin spring? Could your sear spring be a bit slack?

Maybe the overtravel screw is turned in too far?
...Keep us posted, these things are always good to learn on. This gun is a 1950's Sistema that was completely rebuilt with a brand new slide and barrel. All the springs were replaced with a Wolf service pack that I purchased. A commander hammer was added along with a new safety and beavertail. The stock trigger, sear and disconnector were kept. There is no overtravel adjustment.

I have completely detail stripped the gun to examine/clean it. There are no broken springs and no real apparent wear, but admittedly I probablt don't know what to look for specifically.

I did try swapping in a brand new spare sear spring and it made no difference.

I just sent a new sear and disconnector to the gunsmith and asked that he fit these seeing as the present parts were over 50 years old.

[larryw]

John, for deliberate bump fire, I see your point, but not for inadvertant instances.

[Mute]

Shhhhhhhhhhhh, or the BATF might want 200 bucks from you.

[1911Tuner]

That is WAY too cool to fix! :D

All jokin' aside, I'd have to call BS on your smith's "technique"
diagnosis of the problem. There are a few things that'll cause that to happen...or any combination thereof.

Sear worn or the primary angle is wrong.

Hammer hooks worn into a negative engagement, and
mainspring pressure tries to squirt the sear out of engagment.
May be due to a botched trigger job.

Weak sear spring...fatigue or the result of kitchen table tweaking.
Sear not fully resetting/trigger not fully resetting.

Weak/broken mainspring. Lets the hammer bounce out of engagement
with the sear, usually happens when the hammer hooks have been cut
too short. See botched trigger job.

Worn or improper disconnector.


Technique....Now THAT'S one explanation for burst-fire that I ain't heard yet. Tell this guy to call me!:D

Hope ya get it nailed down,

Tuner

[DMK]

Thank 1911Tuner. I was hoping you'd comment on this thread.

[1911Tuner]

Mighty welcome DMK.

My hunch is that the hammer hooks are too short, worn into a negative
engagement, or a little of both. Most of the time, simple hammer follow due to things bein' a little out of whack is stopped on the half-cock,(reload from slidelock) or just rides the hammer all the way down, but doesn't fire the round.(Trigger pulled) Not always, but usually. Burst fire almost has to happen when the slide goes to battery and jars the hooks out of engagement. A weakened sear or mainspring will make it more likely, but it would eventually happen anyway.

Keep us posted on the fix.

Tuner

[Graystar]

Shhhhhhhhhhhh, or the BATF might want 200 bucks from you. Don't worry, it's home-made :p

[Graystar]

You know, I wonder if, somehow, the sear is getting hung up on something, like a burr, that's not letting it rotate back onto the hammer. I would agree with 1911Tuner's observation...if the hammer is falling off the sear from the half-cock hook, that shouldn't be enough to fire the round. And I can't imagine having worn out the half-cocked hook.

But if the sear isn't contacting the hammer at all, could there be enough force in the hammer, as the slide gets out of the way, to fire the round?

Just brainstorming outloud...

[1911Tuner]

Good point Graystar. possible, but not likely. If a burr was stopping the
sear from getting to the bottom of the hooks, it would probably result in
such a rough trigger pull that he would notice it right off the bat. There IS
a possibility that the sear nose is too short, or the sear pin hole is too
far from the hammer pin hole. If that's the case, the sear may be able to
bounce part-way out of contact with the hooks and jar off on the return to
battery.


But if the sear isn't contacting the hammer at all, could there be enough force in the hammer, as the slide gets out of the way, to fire the round?

Again...possible, but not very likely. The hammer riding the slide wouldn't
have a lot of "snap' behind it like it dies wen the sear gets tripped. If
the firing pin spring was providing nearly zero tension, or the firing pin
was too long, it would be a little more likely.

Hard to diagnose things like this without having the gun on the bench.
About all you can do is suggest the most likely causes and work your way
down.

The short sear theory has a lot of possibilities if the tip of the sear is
catching on the very tip of the hooks. It could easily jar off.

The last thing that occurs to me is that the bottom corner of the disconnector is protruding through the magwell a little. When that happens, the rims of the up-coming rounds can cause hammer follow.
Easy to diagnose with a flashlight or even by running a fingertip against
the inside of the magwell at the back. If you can see or feel that the corner is inside the magwell, that could be it.

Meanwhile, we wait for the gunsmith's report.
Tic tic tic...
Tuner

[BluesBear]

Back around the mid 80's or so one of my shooting buddies fell in love with a selective fire Browning High Power he had fired at Knob Creek.

He was racking his brain trying to find a way to convert his Colt MKIV Series 70 to full auto. His idea was that he could somehow attach the sear directly to the trigger that it would fire until the trigger was released. My position was that the sear needed to control the hammer until the slide went into battery and then release the hammer. After a long session of yes-it-will/no-it-won't we went to the range to decide.

We removed the sear and disconnector so that when you dropped the slide the hammer followed. Well he loaded up a few magazines with 3 rounds and got ready for a few bursts. He pulled the slide back and released it expecting a nice blap-blap-blap. What he got instead was click .
We quit after about 30 minutes. No so much as a mark on any primer.


By removing the firing pin spring we did manage to get a few 2 or 3 round bursts. We quit that when a round fired with the slide held open bythe falling firing pin stop and the case bulged into the feed ramp.
DON'T TRY TO REPEAT THIS TEST.

[Graystar]

Thanks BluesBear. That answer that.

[Rich in VA]

"Sear getting hung up on a burr?"

Sear foot hanging up on disconnector? That would cause it not to reset. Won't do it every time, hard to diagnose unless you have the GS removed. Bit of hard Arkansas/ceramic work will fix it in short order.

Good one.

Rich

[Tamara]

I've doubled a few times on some sub-4lb-trigger 1911's (and one Mateba, but let's not talk about that... :uhoh: ) Like I said earlier, I can see how "technique" can cause "doubles" in a pistol (slack grip combined with poor trigger finger follow-through,) but I'd have a hard time blaming "triples" on that. :scrutiny:

[JohnKSa]

John, for deliberate bump fire, I see your point, but not for inadvertant instances.
So, you're saying that it's more likely that someone could keep exactly the right relationship between grip and trigger by ACCIDENT than on purpose?

I'm not following your reasoning...

[Tamara]

I'm not following your reasoning...

When that second and unexpected *BANG!* happens, your finger tends to move smartly away from the trigger. Unless one has the reflexes of a three-toed sloth on ketamine, a third *BANG!* is quite unlikely to happen.

[1911Tuner]

Rich said:

Sear foot hanging up on disconnector? That would cause it not to reset.

Yet another possibility. This one would probably be accompanied by a
trigger pull that starts out as normal, and gets lighter with successive
shots until it hits the magac spot and goes full auto. If he has noticed
this, that may be the place to look. The corner of the disconnector
protruding into the magwell will often mimick the normal/light trigger when
a hard magazine change is done. Normal trigger...reload...light trigger.
Have seen this cause a slam-fire as the magazine is slammed home.

To check for sear reset, rack the slide by hand on an empty chamber...ride the slide to battery instead of letting it fly...and pull back on the hammer.
Listen closely. If you hear a *click* as the hammer is pulled past full cock,
the sear isn't fully resetting.

tic tic tic...

Tuner

[DMK]

This one would probably be accompanied by a
trigger pull that starts out as normal, and gets lighter with successive
shots until it hits the magac spot and goes full auto. Haven't noticed any strangeness like that.

I'm going to give the 'smith his opportunity to make it right. So far he's been a pretty ethical guy. It might not even be his fault. Don't forget, I had him put in a new hammer on a 50 year old sear and disconnector. I'll let you know what the result is when I get it back.

[DMK]

Well, I promised an update when the problem was resolved. The 'smith sent the gun back to me and it's now working fine. I can't get it to bumpfire at all. It appears that the problem was the sear. It was apparently rounded off a little and too short :confused: Either way, I had him fit a brand new sear and disconnector that I had.

He made good, fixed it and didn't even charge for shipping it back to me. The pistol now shoots and functions like a dream. Me happy. :)

[MaterDei]

Hmmm...

:scrutiny:So what I need to do is round off and shorten my sear a little bit, huh?

[Highland Ranger]

had a brand new Kimber Stainless Gold Match II that bump fired (doubles) a few times right out of the box.

I was intentionally limp wristing it; when I held tight, no problem.

Keep in mind that the Gold Match has a real short light trigger pull . . . .

[DMK]

Hmmm...

:scrutiny: So what I need to do is round off and shorten my sear a little bit, huh? MaterDei, I'll sell you my old one, cheap. :D

[Jammer Six]

My hunch is that the hammer hooks are too short, worn into a negative
engagement, or a little of both.

Could you please explain the term "negative engagement"?

The only thing I can think of that it would mean is that the sear isn't engaging the hammer at all. Any engagement would be positive, wouldn't it?

Anyway, why is it called "negative engagement", and what, exactly does it mean?

Is it jargon?

[1911Tuner]

Jammer asked:

Anyway, why is it called "negative engagement", and what, exactly does it mean?
-------------------------------

Howdy jammer. It means that the hammer hooks are cut at such an angle
that they try to push the sear out of engagement. Positive engagement
pulls the sear deeper into the hooks...Square hooks have a neutral
engagement. Sometimes the hooks can wear into negative engagment.
Sometimes they're not cut correctly. Either one is dangerous.

With negative engagement, setting a dial indicator on the hammer will
show forward movement when the trigger is pulled slowly..or uncocking
the hammer. Positive will show the hammer to move backward in a cocking movement. Square hooks...neutral engagement..will show no movement
of the indicator.

With a negative engagement, the tension of the mainspring will try to
squirt the sear out of the hooks...and will cause hammer follow during the cycle, and even burst-fire if it's bad enough, especially when the sear spring gets a little tired.

Find a picture of the hammer and sear in the installed position and study it a minute. It'll come clear.

Cheers!

Tuner

[Jammer Six]

Find a picture of the hammer and sear in the installed position and study it a minute. It'll come clear.


Your explanation did it for me. Thank you.

Now, how come the math teacher couldn't explain that damn pair of trains that clearly?
:cuss:

I'd be very interested in seeing a picture of how you set up the dial indicator- I can see how it would be very easy to get either positive or negative engagement without realizing it, and I can imagine the problems they would create. I can see why I would want to avoid either, and I can see how the dial indicator would tell the real truth.

I imagine there's at least one vise involved.

I'm older than I used to be, and I've learned how to recognize wheels that have already been invented.

[1911Tuner]

Easy, Jammer...and there's one vise.

The pistol goes into one...sans grip panels, and the magnetic base indicator
sits on a steel plate that's fastened to the edge of the bench with a C-clamp. Hint: If your trigger has a lot of creep, it's a good bet that the
hooks aren't square. Either that, or they're .030 long.:D

I can live with a little positive engagement..and a 6-pound trigger.
Negative worries me, though.

Cheers!

Tuner

[LynnMassGuy]

My SKS it slam-fires when the firing pin gets gummed up. It goes full auto for a few rounds. I don't see why the same thing couldn't happen to a pistol. My buddies 910 has done it when he doesn't keep it clean.

[boing]

It can and does happen to pistols, but the protruding firing pin tends to prevent the rim of the case from sliding up the breechface, causing a stoppage. Rifles that snap the extractor over the rim from behind as the action goes into battery are more susceptible to the problem.